1. Field of the Invention
This invention relates to processors, and more particularly, to balancing performance and power consumption in processors.
2. Description of the Related Art
During the design of a computer or other processor-based system, many design factors must be considered. A successful design may require several tradeoffs between power consumption, performance, thermal output, and so forth. For example, the design of a computer system with an emphasis on high performance may allow for greater power consumption and thermal output. Conversely, the design of a portable computer system that is sometimes powered by a battery may emphasize reducing power consumption at the expense of some performance.
In some computer systems, an operating point (e.g., a clock frequency and operating voltage) may be adjusted according to a workload. In such systems, a compute-bounded workload (i.e. one that is processor intensive) may cause a processing node to be operated at a higher operating point, whereas a memory-bounded workload (i.e. one that includes a large number of memory accesses, which may involve large latencies) may cause the processing node to be operated at a lower operating point. For example, in some computer systems, a ratio of the amount of time in an active state to a total amount of operational time (i.e. active state and idle state) may be calculated by operating system software for a given interval. If the ratio exceeds a certain threshold, the processing node may be operated at a higher operating point. Otherwise, operations may occur at a lower operating point. Typical intervals for performing the calculation may range from 30-100 milliseconds, with some advanced systems performing the calculation as frequently as every 10 milliseconds.